Fluid heater control



Jan. 12, 1937. N, w. sTlRLlNG FLUID HEATER CONTROL Filed April 26, 1934 INVENTOR Nm MSW/ffy BY /R @kwh Y @ssh /s jATTORNEY Patented Jan. 12, 15937 UNITED STTS ATENT GFFICE FLUID HEATER CONTROL Norman W. Stirling, Plainfield, N. J., assigner to The Texas Company, New York, N. Y., a corporation of Delaware Application April 26, 1934,` Serial No. 722,441 2 Claims. (Cl. 196-132) This invention relates to a control for a iluid In accordance with the present invention, heater, and more particularly to a control for a there is associated with the temperature control tube still of the type adapted to heat a continuwhich regulates the supply of fuel to the burner, ously iiowing stream of oil under pressure for an auxiliary control which is responsive to the cracking or distillation purposes. pressure of the flowing stream of oil or fluid be- 5 It is known to control the operation of a fluid ing heated, and which functions to automatically heater or tube still of this type by regulation of terminate the supply of fuel to the burner when the quantity of fuel supplied to the burner or the pressure of the flowing stream drops below a furnace which heats the owing stream of oil predetermined minim For purposes of illusor fluid, by increasing the supply of fuel when tration, the invention is shown as applied to a 10 the temperature of the flowing stream at a setube still heater for oil cracking or distillation; lected point in the path of flow thereof falls bebut it is to be understood that the invention is low a predetermined value, and decreasing the also applicable to other types of uid heaters. supply of fuel when the temperature of the flow- Referring to the drawing, which illustrates a ing stream rises above a predetermined value. preferred embodiment of the invention, the 15 In a tube still heater of this type, oil is generally single ligure is a diagrammatic View of an oil supplied through a heating coil in a continuously tube still, with the temperature and pressure flowing stream of small cross sectional area by a control of the present invention embodied pump, which maintains the oil under high prestherein.

sure, such as from about 50 to 100 pounds per The usual furnace of the tube still is indicated 20 square inch or more, as it flows through the coil. at l0, having a heating coil Il therein, and

The temperature control mentioned above has which may be located in the convection or radibeen used to maintain the outlet temperature ant heating sections, or in both sections, in the of the oil as it discharges from the heating coil customary manner. Any suitable type of tube substantially constant at a value depending upon still or coil heating furnace may be employed.

the operation being conducted, and which may Oil to be heated is drawn from a suitable source be about 600 F. to 900 F. or higher in the case of supply through pipe I2 by pump I3 and forced of a crackingv or distillation still. In order to under pressure through line Hi to the heating maintain such a high outlet temperature of the coil I l. The continuously flowing stream of oil continuously flowing stream of oil, which is genis discharged by line l5 containing valve I6 into 30 erally passed through the heating coil at high a suitable treating chamber I1, which may be velocity, high furnace temperatures are maina soaking drum or ash distillation chamber or tained by the supply of considerable quantities other treating device as is customarily employed of fuel and air for combustion purposes. Under with a tube still heater.

such conditions, the maintenance of the heating Heat is supplied to the furnace of the tube still 35 coil in proper operating condition depends upon by a burner 20, to which a suitable fuel, such as the continuous supply of oil thereto under presgas or fuel oil, is supplied by line 2l from a suitsure and flowing at high velocity to prevent obable source of supply. Positioned with line 2l is jectionable coke deposition within the tubes due a control valve 22, which is adapted to regulate to decomposition of the oil. It sometimes hapthe supply of fuel to the burner. Any suitable 40 pens that there is a failure of the oil supply, due form of regulating valve or other type of control to a break down of the oil pump or to a failure for the supply of fuel may be employed. That of the power supply to the prime mover driving shown is a pressure responsive valve of the balthe pump, or for other reasons. Should this ocanced type. The stem 23 of the valve is connected cur, excessive coking of the tubes of the heating to a suitable diaphragm 24 mounted within cas- 45 coil usually results, and bulging and splitting of ing 25, to which a. pressure control uid is supthe heater tubes may occur, necessitating a plied above the diaphragm by line 26. A line 21 costly shutdown for cleaning or repair. extends from the line 2| to the casing 25 beneath It is an object of the present invention to prothe diaphragm 24, so that the under side of the vide in conjunction with the temperature control diaphragm is responsive to the pressure of fuel of a fluid heater of this character, a safety conbeing supplied to the burner. A suitable valve trol which will automatically terminate the supcontrolled bleed 28 is provided for the under side ply of fuel to the burner upon an interruption of the diaphragm, and a similar valve controlled in the proper supply of oil or other fluid to be bleed 29 is shown for the space above the diacV heated through the heating coil. phragm. In the normal functioning of the valve, f

the pressure of control fluid from line 26 above the diaphragm is balanced by the pressure of fuel supplied through line 2l and communicated to the space beneath the diaphragm by line 21, so that the valve floats in a partially open position. Any change in pressure of control fluid above the diaphragm temporarily destroys the equilibrium, and is accompanied by a corresponding movement of the diaphragm and valve, whereupon the pressure of the fuel communicated through line 21 is correspondingly changed and the valve regains an equilibrium in its new setting. A by-pass 30 controlled by valve 3|` is provided around the regulating valve 22, so that the by-pass can be used when starting up the tube still, communication of valve 22 with the line 2| being then closed by block valves 32 and 33. When the plant has been started and is functioning normally, valve 3| can then be closed and valves 32 and 33 opened, so that the regulating valve 22 is then brought into operation.

Any suitable pressure fluid may be employed for actuating valve 22. As shown, compressed air from a suitable source of supply is passed through. line 35 to a liquid trap 36, where condensed liquid or moisture is removed by leg 31, the air then passing by line 38 to a suitable automatic temperature controller indicated. at 4D. This controller is adapted to regulate the pressure of the control fluid supplied to casing 25 above diaphragm 24 by line 26. The actual pressure of the control fluid in line 26 is regulated in accordance with the temperature of the oil flowing through the coil I I, by a pyrometer 42 positioned adjacent the outlet of the coil I I, and connected to the controller by electrical leads 43 and 44. The controller is set to maintain a predetermined temperature at the outlet of the heating coil. Should the temperature of the oil at ,this selected point increase beyond the predetermined normal, the controller then functions to decrease the pressure of air or control fluid in line 26, which allows valve 22 to move toward closing position to thereby decrease the supply of fuel to the burner, which restores the temperature of the oil to the desired normal. Conversely, upon a decrease in oil temperature at pyrometer 42 below the predetermined temperature, controller 49 acts to increase the fluid pressure in line 26 and move v-alve 22 toward fully open position, thereby increasing the supply of fuel to the burner and restoring the temperature of the heated oil to normal. Temperature controllers of this type which function to control the flow or pressure of a fluid in accordance with temperature variation in another fluid being heated are known,for example, see patent to de Florez No. 1,768,353, dated June 24, 1930. As any suitable conventional type of temperature controller may be employed, no further description of such an instrument is though necessary. While the controller is shown as responsive to the temperature of the oil adjacent the heater outlet, it is to be understood that it may be made responsive to the temperature of the oil at any other point in its path of flow by a suitable positioning of the pyrometer, or to the temperatures of the oil at several different points i-n its path of flow by an arrangement of pyrometers connected in series or parallel as is well understood.

Positioned within line 26 is an auxiliary control valve 44, the stem 45 of which is connected to a diaphragm 46 mounted within casing 41. A line 48 extends from the oil supply line I4 on the pressure side of pump I3 to the space above diaphragm 46, so that the oil pressure normally forces the diaphragm 46 and valve 44 down t0 fully open position. The pressure responsive valve 4I can be spring loaded by a suitable spring 49 surrounding stem 45 and acting upwardly, so that the valve 44 is closed by the spring when the pressure of the iiowing stream of oil within the line I4 falls below a predetermined minimum at which the spring loaded valve is set. The auxiliary pressure responsive valve 4I is thus normally open so that it does not interfere with the supply of control fluid to the fuel Valve 22, as regulated by the temperature controller 40. However, should abnormal operating conditions occur in the oil supply line and the pressure drop therein below the predetermined normal, such as would result from a failure of pump I3 or an exhaustion or stoppage of the oil supply from line I2, the resultant decrease in pressure within the oil line will automatically close valve 4I and thus shut off the supply of control fluid to the space above diaphragm 24. The existing pressure-beneath the diaphragm will then fully close valve 22 and terminate the supply of fuel to the burner 20'. This will rapidly shut down the tube still and thereby prevent injury to the heating coils. The pressure control is thus combined with the temperature control, so that a single control fluid system may be employed, with resultant economy in installation, and reliability in operation.

While the invention has been particularly described in connection with the supply of heat through the regulation of the supply of fuel to a burner, it is of course applicable to the control of heat of an electrical heater, where the pressure control fluidis caused to actuate a suitable switch or rheostat supplying current to the heater as will be readily understood.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departing from the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

I claim: f

i. In a fluid heater, having a burner with means for controlling the supply of fuel thereto, a heating coil adapted to be heated by said burner, and a pump for forcing a fluid to be heated throughthe heating coil in a continuous stream under pressure; a source of control fluid under pressure, a control iiuid line connecting said control fluid source to said fuel controlling means whereby said controlling means is actuated in response to the supply of control fluid, regulating means for the supply of said control fluid, thermostatic means responsive to the temperature of the fluid being heated for actuating said regulating means to vary the supply of fuel to said burner in accordance with the temperature of the fluid being heated, and means located between said pump and the outlet of said heating coil responsive to the pressure of said flowing stream of fluid being heated, said last mentioned means being operably connected to the said control fluid line for modifying the supply of said control fluid to the fuel controlling means to thereby entirely cut off the supply of fuel to said burner when the pressure of said iiowing stream of fluid drops below a predetermined minimum.

2. In a` tube still having` a furnace provided with a burner and a fuel line supplying fuel to said burner, a pressure responsive fuelvalve for controlling the supply of fuel to said burner, a heating coil within said furnace, and a pump for forcing oil in a continuous stream under pressure through said heating coil; a source of supply of control fluid under pressure, a control fluid line connecting said control fluid source to said pressure responsive fuel valve whereby said fuel Valve is actuated in response to the pressure of control fluid supplied thereto, regulating means for the supply of control uid to said valve including thermostatic mechanism responsive to the temperature of the flowing stream of oil adjacent the outlet of said heating coil and adapted to increase or decrease the supply of fuel to said burner upon a decrease or increase respectively in the temprature of the oil, to thereby maintain the oil outlet temperature substantially constant, a pressure responsive valve within said control fluid line, said valve being normally open, and a line from said flowing stream of voil located between said pump and the outlet of said heating coil, said line. being operably connected to said last mentioned pressure responsive valve for modifying the supply of said control fluid to the rst mentioned pressure responsive fuel valve to thereby entirely cut off the supply of fuel to said burner-when the pressure of the flowing stream of oil drops below a predetermined minimum.

NORMAN W. STIRLING. 

